The invention of the sewing machine changed the method of manufacturing garments, and helped to establish a garment industry. Consequently, the so-called "one needle with one thread" motto of the traditional style of making clothes has vanished into history.
The original sewing machine, like the other industrial products of the same era, was operated by human power. The typical sewing machines in the 1950's were operated by means of a foot pedal. However, after a certain amount of pedaling has taken place, the operator tired easily. Due to the daily pedaling, the calf muscles became well developed, and a professional tailor could readily be identified by such well developed calf muscles.
Some years following the invention of the first foot-operated sewing machine, electric power replaced human power. This revolution significantly improved the operation of the sewing machines and drastically reduced the consumption of human power. Hence motorized sewing machines replaced the traditional foot-pedal operated sewing machines of the earlier era.
In addition to industrial sewing machines for the mass manufacture of garments, motorized sewing machines for home use, which were, however, relatively heavy, became available. In a further developmental step, a more portable hand-held sewing machine, operated by means of a D.C. motor, appeared on the market.
Because of the compactness of the latter type of sewing machine, its easy operability and convenience in terms of the power supply, it became very popular with housewives. A typical mini-sewing machine of this type was described about 13 years ago in Chinese Pat. No. 7227261.
Both the traditional, and the conventional mini-sewing machine were provided with a driving mechanism which included a gear mounted on the revolving shaft of a D.C. motor, so as to engage a large steering gear, which latter drove another even larger gear. A crank shaft connected that still larger gear to the frame body. The rotation of the motor was thus converted to a vertical reciprocating movement suitable for the sewing process.
Even though the conventional mini-sewing machine is compact and easy to operate, it still has some drawbacks, which are further enumerated hereinbelow.
(1) High rate of power loss. The more transmission gears are employed, the greater the power loss due to unavoidable friction losses, and the greater the power required to operate the machine.
(2) A multiple number of gears leads to greater wear and tear on individual gears, and the cumulative wear and tear is even greater still, and after a certain time, interferes with a smooth sewing operation.
(3) The increased wear and tear enumerated in the previous paragraph eventually leads to a breakdown of the entire machine.